I quilted my first quilt on my lightweight brother machine. Big mistake. Not only did it not turn out very pretty. It totally frustrated me, AND destroyed my machine. I was told at the repair shop that it would cost more to fix it than buying another one. The cheaper machines are not made to withstand the stresses of the weight of all the layers tugging the mechanism (not very technical... sorry)
The good news is I now have a beautiful new Pfaff quilting machine/